#include <iostream>
#include <cfloat>
bool hmean(double a, double b, double *ans);

int main()
{
	double	x, y, z;

	std::cout << "Enter two numbers: ";
	while (std::cin >> x >> y)
	{
		if(hmean(x,y,&z))
		{
			std::cout << "Harmonic mean of " << x << " and " << y << " is " << z << std::endl;
		}
		else
		{
			std::cout << "One value should not be the negative " << "of the other - try agian.\n";
		}

		std::cout << "Enter next set of numbers <q to quit>: ";
	}
	std::cout << "Bye!\n";
	return 0;
}

bool hmean(double a, double b, double *ans)
{
	if (a == -b)
	{
		*ans = DBL_MAX;
		return false;
	}
	else
	{
		*ans = 2.0 * a * b / (a + b);
		return true;
	}
}

